1. Field of the Invention
The present invention relates to a rasp attachment for a motor-driven hand-held device for taking off bones or other solid tissue.
2. Description of the Related Art
In numerous surgical operations bone substance is taken off by filing, rasping, planing or milling in order to model bone surfaces. This is, for example, required to remove a narrow pass situation, prepare the insertion of an implant or post-process surface structures which resulted from a previous coarser processing step. Subsequently, an example from shoulder surgery is described.
At the human shoulder, an anatomic variant of the akromion frequently leads to a bone narrow pass situation which is referred to as the impingement syndrome in the English-speaking world. This narrow pass situation mainly leads to chronic movement and stress-dependent pain in the shoulder area in the middle phase of life. Frequently, the chronic, mechanical irritation also leads to progressing damage of a tendon cuff located below the akromion, the rotator cuff. For treating the impingement syndrome the extension of the slip space below the akromion has been accepted worldwide. FIGS. 5 and 6 show schematic illustrations of the shoulder roof in the longitudinal section or sagittal section, respectively, in two different stages of treatment.
FIG. 5 shows the acromion 10, the humerus head 12 and the intermediate rotator cuff 14 in the original state. The outer rim 16 of the acromion 10 is drawn down too far, so that the movement of the shoulder joint or the humerus head 12, respectively, in the acromion is restricted. The subsequently illustrated surgical operation is referred to as acromioplastics.
In classical acromioplastics according to the specification of the first author (Neer) the acromion is changed using a chisel. In the last few years, an oscillating saw has mainly been used for the treatment of the acromion 10. By using the oscillating saw, two saw cuts 22, 24 are performed in order to remove the excessive rim 16 of the acromion 10. Using the saw, however, only straight or level saw cuts, respectively, may be generated. At the bottom side 26 of the acromion 10 facing the rotator cuff 14 or the humerus head 12, respectively, an edge 28 thus results at which generally a flash remains. This flash is subsequently removed using a hand-held rasp or a cherry. This process is tiring, however, and not very tissue-conserving.
Depending on the severity of the deviation of the shape of the acromion 10 from the ideal standard, in acromioplastics further the bottom face or bottom side 26, respectively, of the acromion is thinned in order to extend the slip space of the shoulder joint. The state of the acromion 10 after the acrominoplastics is shown in FIG. 6. Dashed lines indicate the contour of the acromion 10 before the operation and before thinning. The edge 16 of the acromion 10 was removed by the sawing cuts 22, 24, and at the bottom side 26 of the acromion 10 a layer 30 was removed in order to form a new bottom side 26′ of the acromion 10.
The state represented in FIG. 6 illustrates an ideal state. Generally, a concave shaping of the bottom face 26 of the acromion 10 may not be achieved using the hand-held rasp, however. A further disadvantage of the prior art is, as it was already indicated, that the use of a hand-held rasp or a cherry for processing the acromion 10 is tiring and not very tissue-conserving.
From U.S. Pat. No. 6,048,345 A a medical device in the form of a file for removing and forming solid body materials is known. A file-head which may comprise different shapes is connected to means for reciprocately moving the file-head via an arm portion.
From WO 93/15665 A a surgical instrument is known including drive means for reciprocating a cutting means comprising a rasp face.
EP 0788773 A1 discloses a tool for implanting an endoprosthesis in a cavity of a human bone. The tool contains a rasp body which corresponds to the prosthesis shank to be anchored in the bone cavity. At the proximal end of the rasp body a hand-grip is removably mounted.
EP 0634145 A1 discloses a hollow shank rasp for the preparation of a hollow bone for the reception of a stem-shaped endoprosthesis. Proximally a hand-grip may be attached to the hollow shank rasp.